Prothrombin Time (PT and INR)
Test Code
PT2
Description
Collect
Blue top tube.
Specimen Preparation
Onsite [NJH]: Transport to lab within 1 hour.
Offsite: Separate plasma from cells within 2 hours by centrifuge and aliquot into a labeled polypropylene or similar plastic tube.
Preferred volume: 1 mL plasma
Pediatric Collection
Minimum volume: 0.5 mL
Unacceptable Conditions
Sample will be rejected if Blue top tube under-filled.
Clotted and hemolyzed specimens will also be rejected.
Storage Transport Temp
Offsite: Frozen. Send plasma Priority Overnight via FedEx and in a well insulated container on dry ice.
Stability
Stability after cell separation:
24 hours at RT (15-25°C ),
refrigerated unacceptable,
2 weeks frozen at ≤ -20°C
1 year frozen at ≤ - 70°C
Notes
Make sure Blue top tube is filled properly to assure proper ratio of anticoagulant to whole blood.
Performed
Mon-Fri
Methodology
Chromogenic
Reported
4 hour routine, 1 hour STAT
Department
Core LabSynonyms
Protime; INR; Prothrombin Time; PT
Reference Interval
| Unit = Seconds | Range | Age Group |
|
Protime [PT] |
9.5-12.1 |
All |
| INR | 0.8-1.2 | Normal patient 0.9-1.1 |
| INR | 2.0-3.0 | Treatment/venous thrombosis |
| INR | 2.0-3.0 | Pulmonary embolis |
| INR | 2.0-3.0 | Prophylaxis/venous thrombosis |
| INR | 2.0-3.0 | Systemic embolization |
| INR | 2.5-3.5 | High risk patients with heart valves |
CPT Code
85610